@thomasfuchs I'm thinking about it like a system of equations of three variables. We can easily find the "equations" the for the first two "variables" (the star positions in the image, the comet's position in the image), but to be able to "solve" the entire system we need a third "equation" that's independent of the first two. In this case it's the ephemeris data of the comet.
Scientists track the path of the comet, and we could use that data to compute something...
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